The present invention relates to an integrated circuit (IC) card containing integrated circuits such as a microcomputer and a memory unit, and particularly, to an IC card provided with indication means for indicating history or curriculum information or updated information to thereby avoid wasteful recording of varying data, obtain a rapid access and enable a versatile application, and capable of not reading unnecessary information.
An IC card or so-called smart card is produced in various shapes, for example, there exist a flat card, a key-shaped card, and a rod-shaped card. The IC card of the present invention covers all of these cards.
An IC card contains elements such as a microprocessor (CPU) and a memory unit and hence is a smallsized information processing system having functions of decision and storage. Consequently, the data integrity and security can be further enhanced as compared with the conventional magnetic card such as a credit card or a bank card. Furthermore, since the storage capacity has been greatly increased through the advance of the IC technology, the IC card is regarded as efficient for the information storage card.
For the memory unit of an IC card, a nonvolatile IC memory such as an erasable, programmable read-only memory, EPROM in which stored data can be erased by ultraviolet radiation or an electrical, erasable, programmable read-only memory, EEPROM is used, and hence the storage contents can be kept therein without requiring a power source to be integrated in the card. Consequently, the memory unit can be produced in a simple structure and is thus adopted as the primary storage means of the IC card at present. However, a volatile IC memory such as a random access memory, RAM can also be used as the memory of the IC card if a long-life power supply such as a battery is built in the IC card to keep the contents thereof, or as means for temporarily saving storage contents therein from another memory without integrating a power supply in the card.
In the past, data is generally stored in the IC memory as follows. A storage area having an appropriate size is allocated in the IC memory, and then the information of data is sequentially written beginning from an end thereof.
The entire information thus stored is conventionally read out at a time; or various information items are respectively stored in a plurality of storage areas, and a desired information is read by specifying the storage area number associated with the infromation, thereby retrieving the information from each storage area.
Information stored in the memory of an IC card is subjected to renewal or change at times. However, once information is written in a certain storage area of a ROM used as a memory unit, erasing the writen information and re-writing data to be renewed or changed in that area are not possible. Therefore, information should be written one after another in the order of time sequence beginning from one end of the storage area. Consequently, to read a desired information from those written in such a manner, it is necessary to read the information sequentially in writing history until the desired information is read.
With the IC crd whose information is read in the units of storage area, it is necessary to read the entire contents of a storage area sequentially in time (or in the order of history) from the beginning even if only a portion of the information in the storage area, e.g., the latest information thereof, is required. Therefore, there arise some problems that it takes a substantial time to read the desired information and that unnecessary information is sequentially read until the desired information is read, which impedes data sequrity.
Apart from the above, it is desirable in some cases to read the written information sequentially in time depending upon the types or applications of the information. Thus, an IC card has been desired which is capable of both reading only the latest information quickly and reading the information sequentially in the order of history. In addition, in case where erroneous or incomplete information has been written or in case where particular past information is desired not to be read, these unnecessary information should not be read in case of one of the above two methods reading the information sequentially in the order of history since it takes a waste time for reading necessary information.